Multi-tenancy strategies with Spring Data JPA.

1. DB per Tenant:

Each tenant has its own physical database instance. High isolation, high cost.

2. Schema per Tenant:

One database instance, but each tenant has its own schema (namespace). Good balance of isolation and cost.

3. Shared Schema (Discriminator):

All tenants share the same tables. A tenant_id column distinguishes between them. Easiest to scale, requires strict logic to prevent data leaks.

Implementation:

Use a AbstractRoutingDataSource to dynamically switch databases based on the current tenant's context (stored in a ThreadLocal).